TRIPOLI, Libya – NATO launched its most intense bombardment yet against Moammar Gadhafi’s stronghold of Tripoli Tuesday, while a senior U.S. diplomat said President Barack Obama has invited the Libyan rebels’ National Transitional Council to open an office in Washington but stopped short of formal recognition.

The international community has stepped up airstrikes and diplomatic efforts against the regime in a bid to break a virtual stalemate, with the rebels in the east and Gadhafi maintaining his hold on most of the west.

The NATO airstrikes struck in rapid succession within a half-hour time span, setting off more than 20 explosions and sending up plumes of acrid-smelling smoke from an area around Gadhafi’s sprawling Bab al-Aziziya compound in central Tripoli.

Government spokesman Moussa Ibrahim said at least three people were killed and dozens wounded in NATO strikes that targeted what he described as buildings used by volunteer units of the Libyan army.

NATO said in a statement that a number of precision-guided weapons hit a vehicle storage facility adjacent to Bab al-Aziziya that has been used to supply regime forces “conducting attacks on civilians.” It was not immediately clear if the facility was the only target hit in the barrage. Bab al-Aziziya, which includes a number of military facilities, has been pounded repeatedly by NATO strikes.

At the Tripoli Central Hospital, the bodies of three men in their twenties lay on stretchers, their clothing ripped and their faces partially blown away. A nurse, Ahmad Shara, told foreign reporters taken on a government-escorted visit to the facility soon after the strikes that the men were standing outside their homes when they were killed, presumably by shrapnel.

One man who identified himself as a relative pounded a wall and cried out in despair after seeing the bodies. Some 10 other men and women were wounded.

“We thought it was the day of judgment,” said Fathallah Salem, a 45-year-old contractor who rushed his 75-year-old mother to the hospital after she suffered shock. He said his home trembled, his mother fainted and the youngest of seven children screamed in terror at the sound of the rolling blasts.

“You were in the hotel and you were terrified by the shaking — imagine what it was like for the people who live in slums!” Salem told the reporters.

“Honestly, we used to have problems (with the regime),” he said in Arabic. “But today we are all Moammar Gadhafi.”

The U.S. launched the international air campaign on March 19 after the passage of a U.N. Security Council resolution to protect civilians after Gadhafi sent his forces to crush the public uprising against his rule. NATO, which has taken over the airstrikes, says it has been doing its best to minimize the risk of collateral damage.

The alliance has been escalating and widening the scope of its strikes over the past weeks, increasing the pressure on Gadhafi, while many countries have built closer ties with the rebel movement that has control of the eastern half of Libya.

Jordanian Foreign Minister Nasser Judeh announced Tuesday that his country has recognized the rebels’ National Transitional Council as the legitimate representative of the Libyan people and would soon name a permanent envoy in Benghazi.

Several other countries, including France and Italy, have recognized the rebel administration, while the United States, European Union and others have established a diplomatic presence in Benghazi.

Jeffrey Feltman, Assistant Secretary of State for Near Eastern Affairs, said he had delivered an invitation on Obama’s behalf to the rebels to establish a representative office in Washington — a move he called “an important milestone in our relationship with the National Transitional Council.”

But while he said the United States considers the council a “legitimate and representative and credible” body, he stopped short of formal recognition due to what he called the temporary nature of the council. Council members stress that they will represent Libyans only in the period until Gadhafi can be defeated and democratic elections held.

“We are not talking to Gadhafi and his people. They are not talking to us. They have lost legitimacy,” Feltman told reporters during a visit to the de-facto rebel capital of Benghazi.

Feltman also said he expects Congress to vote soon to allow frozen regime assets in the U.S. to be used for purely humanitarian aid in Libya.

Rebel leaders welcomed the diplomatic contact, but said only better weapons will help them defeat Gadhafi.

“It is just not enough to recognize (us) and visit the liberated areas,” spokesman Abdel-Hafidh Ghoga told The Associated Press. “We have tried very hard to explain to them that we need the arms, we need funding, to be able to bring this to a successful conclusion at the earliest possible time and with the fewest humanitarian costs possible.”

Rebels now control the populated coastal strip in the country’s east and the western port city of Misrata, which Gadhafi’s forces have besieged for months. They also control pockets in Libya’s western Nafusa mountain range.

In what would be a significant new deployment of firepower, French Defense Minister Gerard Longuet said Monday that France and Britain will bring in attack helicopters for use in the airstrikes. However, Britain said Tuesday that it has not made any such decision.

British armed forces minister Nick Harvey told Parliament that he couldn’t comment on what the French were saying, but he insisted “that we have not taken this decision, and that we have not suggested to the French that we have taken this decision.”

Harvey left open the possibility that Britain would throw helicopters into the fight, but insisted that Britain was — as of Tuesday — merely considering its options.

The use of helicopters would mark a new strategy for NATO, which has seen Gadhafi’s forces adapt, often turning to urban fighting to make strikes by fighter planes more difficult.

Nimble, low-flying helicopters can more easily carry out precision strikes than jets, but they are also more vulnerable to ground fire. The alliance has had no military deaths since it began enforcing a no-fly zone on March 31.

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Faul reported from Benghazi. Associated Press writer Jamal Halaby in Amman, Jordan, and Raphael G. Satter in London contributed to this report.

AJDABIYA, Libya – Moammar Gadhafi’s forces poured rocket fire after dawn Saturday into Misrata, the only western city still in rebel hands, and weary residents who have endured more than a month of fighting angrily lashed out at NATO for failing to halt the deadly assault.

Five civilians were killed in a 30-minute barrage of shelling that heavily damaged a factory for dairy products and sent up a thick column of black smoke, a doctor said. A human rights group has accused the Gadhafi regime of using cluster bombs in Misrata — munitions that can cause indiscriminate casualties and have been banned by most countries. The Libyan government and military denied the charge.

In eastern Libya, fierce fighting left seven rebels dead, 27 wounded and four missing as the anti-Gadhafi forces sought to push toward the strategic oil town of Brega, according to Mohammed Idris, a hospital supervisor in the nearby city of Ajdabiya. The battle took place on a road halfway between Ajdabiya and Brega.

Frustration was growing among residents in Misrata, where Gadhafi’s troops have intensified their long siege of the city in recent days. The doctor sharply criticized NATO for failing to break the assault with its month-old campaign of airstrikes.

“We have not seen any protection of civilians,” the doctor said. “NATO airstrikes are not enough, and the proof is that there are civilians killed every day here,” he said.

The theme was echoed in the rebel stronghold of Benghazi, where spokesman Abdel-Hafidh Ghoga told a news conference: “There’s no more room for hesitation or for not standing with determination against what is happening in Misrata and other Libyan cities, because the destruction that Moammar Gadhafi is causing in Libyan cities is great and extensive.”

Rebel fighters in eastern Libya were less critical of NATO. Mustafa Abdul-Jalil, head of the rebels’ National Transitional Council, said this week that without the airstrikes, even Benghazi, Libya’s second-largest city and the rebels’ main stronghold, would be in “complete danger.”

The Misrata doctor said Gadhafi’s forces are taking shelter in residential areas that civilians had fled, apparently confident that NATO won’t risk attacking them there.

But the troops have so far been unable to fully occupy the city of 300,000 people, he said, so instead they are targeting sites such as the dairy plant or the port to prevent the arrival of humanitarian aid.

The doctor, who spoke on condition of anonymity because he feared government retribution, said a civilian who was brought to him had been nearly torn in half by a mortar shell and was not expected to live.

NATO officials have said it is difficult to strike Gadhafi’s forces when in an urban area. NATO did say its strikes on Friday destroyed two tanks in the Misrata area.

At a news conference Saturday night in Tripoli, Maj. Gen. Saleh Abdullah Ibrahim denied that the Libyan military is using heavy weapons in Misrata.

When asked whether the NATO airstrikes have had an impact on the Libyan forces, he said he did not know.

“I am a member of the regular armed forces. This type of information is only in the higher ranks of the armed forces,” he said.

Ibrahim confirmed that prisoners had been taken, but would not say how many.

Rebels in Misrata and the New York-based group Human Rights Watch have alleged that Gadhafi’s forces have been using cluster bombs, which pose particular risk to civilians because they scatter small bomblets over a wide area. Most of the world’s nations have banned the use of the munitions.

Human Rights Watch said its researchers inspected remnants of the weapons found in a Misrata neighborhood and interviewed witnesses.

Ibrahim said the accusations were “unfounded,” adding that Libya did not have “these kinds of weapons in our depot, and no single Libyan has been trained on this.”

“We are calling for those who show these kinds of weapons to give us the material evidence,” he said.

A boat chartered by Doctors Without Borders and carrying 95 Libyans from Misrata — 65 of them injured — arrived Saturday at the Tunisian port of Zarzis, according to the official TAP news agency. Nine people who were critically or seriously injured were taken to a hospital in the town of Sfax.

A lack of medicine, food and water for the 6,000-10,000 people in migrant workers’ camps around Misrata has led to a “catastrophic” situation that is deteriorating daily, said Dr. Helmi Makkaoui, a Tunisian coordinator for the humanitarian aid group.

Rebels in eastern Libya held their positions for four days around the city of Ajdabiya, about 30 miles (50 kilometers) to the east, allowing NATO airstrikes to weaken government forces, said Col. Hamid Hassy.

On Friday, the fighters pushed in to reach Brega’s university campus, just outside the town’s oil port, Hassy said. He added that if the rebels retake Brega, they will bring in engineers to repair any damage to the refinery and oil facilities there.

Brega has already changed hands half a dozen times since fighting began in early March. Explosions that appeared to be from new airstrikes could still be heard Saturday in the area.

Despite the strikes, the rebels ran into staunch resistance Saturday. Three of the seven rebels killed were in a car that was struck by either a rocket or artillery shell near a gas station on the road about 24 miles (40 kilometers) from either city, said fighter Ahmed Bakir.

Ambulances streamed to an Ajdabiya hospital, where doctors treated fighters with severe burns or shrapnel wounds. Bloodstained bandages littered the area outside the hospital and workers hosed down a bloody stretcher.

The latest fighting in Brega pushed the rebels back to the town’s outskirts, said Suleiman Mohammed Suleiman, one of the opposition fighters who was shot in the leg while firing a heavy machine gun from the back of a pickup truck outside Brega.

Suleiman said the rebels could see Brega but were not yet inside.

The NATO-led air campaign has kept rebels from being defeated on the battlefield by the better trained and equipped government forces, but it still has not been enough to completely turn the tide. The rebels have been unable to reach Gadhafi’s heavily defended hometown of Sirte, the gateway to the regime-controlled western half of the country.

Previous rebel advances through Brega and its companion oil center of Ras Lanouf, another 60 miles (100 kilometers) farther on, have ultimately foundered as rebels overextended their supply lines and were routed by the heavier firepower and more sophisticated tactics of the government forces.

In contrast those previous charges and retreats in the past six weeks, the rebels appear to be trying a more gradual advance that might actually result in them holding territory.

At a two-day meeting of NATO foreign ministers in Berlin, the United States and its allies put up a united front on the goals of the alliance’s stalemated military mission in Libya, yet failed to resolve behind-the-scenes squabbling over how to achieve them.

NATO members agreed on paper that Gadhafi had to go to end the crisis, they also made clear that they would not be the ones to oust him.